The present invention relates to a recliner for a vehicle seat assembly of the type having a locking pawl with teeth engaging a toothed sector of a latch gear to hold the seat back in place. More particularly, the invention pertains to the profile of a portion of the pawl teeth.
In two door vehicles, it is typical for the seat back of a front seat assembly to be rotatable forward to a "dump" position. This facilitates ingress and egress to and from the rear seat of the vehicle. The seat back is dumped forward by releasing the recliner mechanism and allowing a biasing spring to rotate the seat back forward. Reclining mechanisms of the type described above, when used in seat assemblies with a dump feature, have a latch gear that includes a radially raised slide face at one end of the toothed sector. When the seat back is in the forward dump position, the slide face of the latch gear confronts the teeth of the locking pawl. Since the slide face is smooth, there is no interlocking between the pawl and the latch gear. This allows the seat back to be returned to an upright position without again having to actuate the recliner mechanism.
One problem with such a recliner mechanism is described with reference to FIG. 1. The latch gear 10 is typically attached to the seat back frame for rotation about the pivot 12. The latch gear 10 includes a toothed sector 14 with a plurality of teeth 16 concentric about the pivot 12. At one end of the toothed sector 16, a slide face 18 is radially raised from the toothed sector. An end face 20 extends between the toothed sector and the slide face 18. The locking pawl 22 is mounted to the seat lower frame for rotation about the pivot 24. Pawl 22 includes a toothed portion 26 having a plurality of teeth 28 complementary to and engagable with the teeth 16 of the latch gear.
When the seat back is dumped forward as shown by the arrow 30, the slide face 18 will move into a position confronting the pawl teeth 26 whereby the recliner mechanism is inoperable to lock the seat back in place. When the seat back is returned to an upright position and the slide face 18 moves beyond the pawl teeth 28, the pawl teeth will once again re-engage with the latch gear teeth and lock the seat back in place.
When the pawl is released to "dump" the seat back, if the pawl 28 is not moved sufficiently away from the latch gear, the corner of the latch gear end face will impact against the end tooth 28 of the locking pawl. This impact can deform the end tooth 28 moving it out of position with respect to the other teeth. This deformation can prevent all of the pawl teeth from properly engaging the latch gear teeth 16. The result is incomplete locking of the seat back.
In a four door vehicle, the seat back may move forward such that the sector "over travels" beyond its lock position creating a similar condition where the sector impacts the pawl teeth and causes deformation of the pawl teeth.
Accordingly, it is an object of the present invention to provide a pawl and latch gear with a tooth profile to minimize or eliminate damage to the pawl teeth caused by impact with the latch gear end face.
The primary focus of attempts to overcome this problem has been the profile of the end face 20. The typical approach has been to form the corner of the end face at an incline relative to the radius of the latch gear to reduce the amount of deformation of the locking pawl teeth. The focus of the present invention however, is directed toward the pawl teeth and provides pawl teeth that are configured to minimize damage caused by impact with the latch gear end face.
A portion of the pawl teeth, at the end of the pawl closest to the slide face, are truncated in height. This results in teeth that are shorter and therefore wider at their distal ends. The shorter height both reduces the likelihood of impact with the latch gear end face and increases the strength of the teeth to resist deformation caused by impact. The end most tooth is the shortest with the teeth gradually increasing in length over the first few teeth of the pawl.
Further objects, features and advantages of the invention will become apparent from a consideration of the following description and the appended claims when taken in connection with the accompanying drawings.